This invention relates to a time detecting switch device for an alarm clock to actuate an electric alarm signaling device at a present alarm signaling time.
The essential mechanism of the conventional detecting device for an alarm clock is a drop-in type mechanism constituted of holes and projections provided for time wheels and corresponding detecting wheels, respectively. This mechanism has a disadvantage that, in setting the alarm signaling time or in adjusting time indication, the corresponding setting knob or adjusting knob can be rotated in only one direction because the wall of the hole and the side face of the projection are shaped vertically straight with each other so as to make the projection drop in the hole instantaneously to attain accurate alarm signaling time detection. Further disadvantage of this conventional mechanism is that the electromechanical transducer is undesirably loaded when the projection escapes out of the hole along the inclined wall of the hole with rotation of the wheels.
In order to overcome those disadvantages, the detecting device according to this invention is provided with a phase detecting type slide contact switch which is more simple in fabrication and less costly.
The object of the invention is attained by constituting phase detecting type slide contact switches with the detecting wheels and the time wheels, either the detecting wheels or the time wheels are made of electric conductive material having projections which are the part of contact means of the slide contact switches.